<!DOCTYPE html>
<html>

	<head lang="en">
		<meta charset="UTF-8">
		<title></title>
		<style>
			* {
				margin: 0;
				padding: 0;
			}
			
			.box {
				width: 350px;
				height: 350px;
				margin: 100px;
				border: 1px solid #ccc;
				position: relative;
			}
			
			.big {
				width: 400px;
				height: 400px;
				position: absolute;
				top: 0;
				left: 360px;
				border: 1px solid #ccc;
				overflow: hidden;
			}
			
			.mask {
				width: 175px;
				height: 175px;
				background: rgba(255, 255, 0, 0.4);
				position: absolute;
				top: 0;
				left: 0;
				cursor: move;
			}
			
			.small {
				position: relative;
			}
		</style>
	</head>

	<body>
		<div class="box">
			<div class="small">
				<img src="images/001.jpg" alt="" />
				<div class="mask"></div>
			</div>
			<div class="big">
				<img src="images/0001.jpg" alt="" />
			</div>
		</div>
	</body>

</html>